Align allowed package names between build and dependencies.

I can compile a project with name 1_Foo, but not use it as a data-dependency. I get

ghc-pkg: 0: Parse of field '
unexpected all digits in portion of unqualified component name

MyProject
' failed.
damlc: callProcess: /Users/bernhardelsner/.daml/sdk/1.5.0-snapshot.20200902.5118.0.2b3cf1b3/damlc/resources/ghc-pkg "recache" "--global-package-db=.daml/package-database/1.8/package.conf.d" "--expand-pkgroot" (exit 1): failed

We should either restrict project names, or fix dependencies with such names. The latter would be better as projects with _ in their name may already exist “out there”, but either is fine.

[bame-da]

Could we make it a warning? Something like “Package names/versions should have format [RegExp]. You may be able to compile packages with different formats, but you will not be able to use them as dependencies in other projects. Unsupported package names or versions may start causing compilation errors without warning.”

[robin-da]

@hurryabit , @bame-da This is a limitation by ghc-pkg. Valid package id’s for ghc-pkg are specified by : https://downloads.haskell.org/~ghc/latest/docs/html/libraries/Cabal-3.2.0.0/Distribution-Types-PackageId.html. In particular, _ is not allowed in package names. My suggestion is to disallow underscores as well since we don’t want to patch ghc-pkg. This would however be a breaking change in DAML-LF. Thus, we could simply throw an error when parsing the package id from the daml.yaml and leave DAML-LF untouched.